Most memories in electronic devices have access transistors that connect and disconnect memory elements from the reading/writing circuits. To obtain access transistors with the desired characteristics, the access transistors and memory are typically fabricated on single crystalline silicon wafers. As the integration density of memory elements increases, the transistors also get smaller. However, as the transistor size shrinks, it becomes increasingly difficult to satisfy the switching requirements and the fabrication cost increases prohibitively. Further, the use of single crystalline silicon access devices can restrict its architecture.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.